Remove Nth Node From End of List

Desicription

Given a linked list, remove the nth node from the end of list and return its head.

For example,

1
2
3
Given linked list: 1->2->3->4->5, and n = 2.
After removing the second node from the end, the linked list becomes 1->2->3->5.

Note:

Given n will always be valid.
Try to do this in one pass.

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution
{
public:
ListNode* removeNthFromEnd(ListNode* head, int n)
{
int total = 0;
ListNode* traver = head;
while(traver){
total++;
traver = traver->next;
}
n = total - n + 1;
if(n == 1)
return head->next;
traver = head;
int cnt = 1;
while(traver){
if(cnt == n - 1){
traver->next = traver->next->next;
return head;
}
traver = traver->next;
cnt++;
}
}
};